This invention relates generally to a mains supply safety socket and, in particular, to such a socket which is childproof. The general features of the invention are applicable to all mains supply sockets whether or not they are provided with a ground outlet. The term "socket" is taken to refer to any type of female connector for connecting a source of electric power to an appliance including, for example, wall and extension electricity supply sockets as well as electric light sockets.
It is known to provide mains supply safety sockets wherein the live and neutral outlets are covered with an insulating plate which is adapted to retract when the ground pin of a three pin plug is inserted into the ground outlet of the socket. It is generally arranged in such systems for the ground pin to be slightly longer than both the neutral and live pins in order to facilitate the operation of the safety mechanism.
One drawback with such a system is that the insulating plate is liable to jam. If it jams in the closed position the socket is unusable, and if it james in the open position the socket is usable but the safety device is inoperative. In either case, an electric cable connecting an appliance to the socket remains unprotected and there constantly exists across its live and neutral cores the full mains supply voltage, whether or not the appliance is switched on. Furthermore, such a system is not childproof in that it is readily appreciated that insertion of a ground pin, or any substitute therefor, will on its own retract the insulating plate, thereby overriding the safety mechanism. Indeed, this approach is sometimes adopted in order to connect the supply leads from an electrical appliance directly to the mains without first attaching a plug to the appliance, and is obviously highly unsatisfactory from a safety point of view.